The invention relates to a process for the production of decorated ceramic material, for example tableware, with increased resistance to cutlery abrasion traces (scratches) and means for such, wherein this means is a decoration coloring substance with a combination of particular characteristics according to the invention, to be used in the process.
The production of colored decorations on ceramic materials, such as, for example, tableware made of stoneware, bone china and porcelain, is known per se (see Ullmann's Enzyklopadie der technischen Chemie, 4th Edition, Vol. 14 (1977), pp. 9-10). By means of the most diverse application techniques, such as painting, immersion, spraying, and in particular direct or indirect imprinting, a decoration coloring substance is applied in the form of a decoration onto the material to be decorated and subsequently fired in.
Decoration coloring substances comprise substantially a pigment and a glass flux conventionally containing one or more glass frits. In the case of tableware decorations, it is necessary to differentiate between on-glaze and in-glaze decoration. After glaze firing, a decoration is applied onto the tableware part to be decorated, most often by means of direct printing or via indirect printing (transfer pattern technique), and subsequently, in the case of on-glaze decoration, the decoration is baked in during normal firing at approximately 780 to 900.degree. C., or in a high-temperature quick firing, at above 900.degree. C. to approximately 1100.degree. C.; and in the case of an in-glaze decoration, baking is at temperatures in the range from approximately 1100 to 1250.degree. C.
Porcelain tableware, in particular hotel and restaurant porcelain, is subjected to high stress through alkaline washwater of dish washing machines and through the effect of cutlery during use. Cutlery effects on decorated tableware parts lead to gray abrasion traces which interfere with the aesthetic impression. Such abrasion traces, or scratches, caused by metal cutlery are especially disturbing in large-area decorations which are increasingly in demand by the market. This problem could, until now, only be partially solved through an in-glaze decoration in which the decoration becomes partially submerged in the glaze layer during the firing. As yet, a way of surpassing this practice and preventing the abrasion traces has not become known.